Any person who has ever ridden a bicycle knows from experience that changing conditions of terrain require different amounts of effort on his part to maintain the forward motion of the bicycle. Generally, on level surfaces we can exert a minimal effort to move along at a reasonable speed, on downhill slopes we “coast”, and to go uphill we must exert maximum effort. The rider learns that in order for him to supply different amounts of energy under different circumstances, he must change the position of his body. For example, for traveling steadily at moderate speed on level ground he can sit up straight in the seat, to race along at rapid speeds he leans forward crouched over the handlebars, and to go up a steep hill he gets maximum power by standing up and putting his weight directly above the pedals and even pulling up on the handlebars. Body shifts are also frequently necessary to maintain balance and to reduce wind resistance, in addition to provide varying amounts of power.
Because of their rigid frames, conventional bicycles are not well designed to accommodate the different positions the body assumes during a journey. The rigid positional relationship between the seat, handlebars, and pedals, forces the designers to use average distances between each of these positions depending on the intended use of the bicycle. The result is that the rider often finds himself riding on a bicycle that is not suited to his size or needs and in a physically uncomfortable position that is tiring to maintain.
Recognizing the problems resulting from the rigid frame of conventional bicycles, various solutions have been proposed. Typical of these are the semi-recumbent bicycles disclosed in, for example, U.S. Pat. Nos. 4,659,098 and 4,925,203. In the typical bicycle of this type, the rider sits in a seat with legs stretched out roughly parallel to the ground and with his feet on the pedals, which are located above the front wheel and in front of the handlebars. This design solves some of the problems, but again the frame is fixed and there is no provision for changing the positional relationship between the seat, pedals, and handlebars during travel. In addition, semi-recumbent and recumbent bicycles are associated with many problems resulting from their design that affect the comfort, health, and safety of the rider.
Another approach to overcoming the problems caused by the rigid frame of the conventional bicycle is shown in FIG. 1. In this case the relative position of the seat and pedals can be adjusted, but the amount of adjustment is limited by the ability of the derailleur to adjust the length of the chain as the front gears move closer to and further away from the rear gears. Most importantly, the adjustment can not be carried out while the bicycle is in motion and requires a separate adjustment of the seat in order to keep it parallel with the ground.
It is therefore a purpose of the present invention to provide a bicycle which overcomes the limitations of the prior art and for which the position of the seat and the pedals can be easily changed relative to the fixed handlebars.
It is another purpose of the present invention to provide a bicycle in which the change in position of the seat and the pedals relative to the fixed handlebars can be accomplished by the rider while riding on the bicycle.
Further purposes and advantages of this invention will appear as the description proceeds.